Tubular electric resistance



Feb. 10, 1931. J. G. BASSIERE d May 16. 1928 Patented Feb. 10, 1931 PATENT OFFICE JEAN GUSTAVE BASSIERE, OF PARIS, FRANCE TUBULAR ELECTRIC RESISTANCE Application filed May 16, 1928, Serial No. 278,118, and in- France June 4, 1927.

The present invention relates to a tubular electric resistance through which a fluid can be circulated.

When an electric current is supplied to said tubular resistance, a part of the heat produced in said resistance is drawn off by the fluid circulating through the tube.

With this arrangement, the whole of the circulating fluid is utilized to absorb the heat of the resistance element, so that the exchange of heat between the resistance and the circulating fluid will be quite considerable, and will take place in particularly favourable conditions.

This exchange of heat may be utilized either for cooling the resistance, or for heat ing the circulating fluid, or for both purposes simultaneously.

Tubular electric resistances are known in which a metallic band of suitable cross-section is formed into a helix with overlapping edges so as to constitute a continuous tubular element. Between the adjacent edges of the successive coils of said helix is inserted a strip of insulating material which serves both for making the tube fluid-tight and for electrically insulating the individual helix coils from one another.

The object of the invention is to provide means whereby a suiflcient lengthwise elasticity is given to order that said tube may be adapted to follow the expansions and contractions due to the great variations in the temperature, and without subjecting the insulating joint to exaggerated stresses prejudicial to its good state.

In the appended drawing, which is given solely by way of example:

Fig. 1 is a sectional view of the metallic band used for the construction of the tubular resistance element according to the invention.

Fig. 2 is a view of a tubular resistance element according to the invention, the lower half of said view being a lengthwise section, the upper half being an external view.

The cross section of the band, as shown in Fig. 1, comprises the edge parts 1 and 2 and the central part 3. In order said tubular resistance in to constitute the tubular electric resistance, the metallic band is formed into a cylindrical, prismatic 0r polygonal helix, so that the edge part 1 of the metallic band in one individual helix coil will cover the edge part- 2 of the metallic band of the adjacent helix coil (Fig. 2).

Between the overlapping edges 1 and 9. of two successive helix coils is inserted an insulating strip a, which is wide enough to extend somewhat beyond the tree edges of the parts 1 and 2 at the interior and at the exterior of said tube, and it will thus insulate the adjacent coils in such-manner that the current passing laterally from one turn to another will be negligible. The insulating band assumes the form shown at 4, Fig. 2.

The resistance tube thus obtained may readily transmit its heat to the circulating fluid. Since the insulating band serves only to provide electrical insulation for the small difference of potential between two adjacent coils, its thickness is but small; a good thermic contact is thus afforded between the edges 1 and 2 of the adjacent coils. Moreover, the surface of the metallic band in direct contact with the circulating fluid is a considerable fraction of its total internal sur face. These conditions will all contribute to assure a very active exchange of heat between the said tube and the circulating fluid.

Due to the curved form of the connection, which is given by way of example, the joint will have a great mechanical strength. The middle part 3 of the said band in its bent form will be sufficient to give the tube a good lengthwise elasticity in order that the stresses caused by expansion and contraction due to temperature changes, to vibrations or to flexions, will 'notexpose the joint to excessive efforts which would oiier prejudice to its preservation.

The metal of the said metallic band employed for the manufacture of the resistance tube may be selected as desired, and this will depend upon each particular application.

In a same manner the material forming the band 4 may difi'er according to the applications of the said resistance tubes; it need not have a very high insulation, since the tension between the coils is but small. It may be also fireproof, and may consist of asbestos or mica if the tubular resistance is employed at high temperatures. It may consist of organic material, such as paper, when operating at low temperatures. v Having now described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A tubular electric resistance comprising a band of electrically conducting material provided between its edges with a yielding longitudinal central portion adapted to expand and to contract transversely, said band being formed into an helix with the edges overlapping on either side of said yielding portion so as to constitute a tubular element having a lengthwise elasticity, and a strip of electrically insulating material inserted be-' tweeen the adjacent edges of said band and independent of said yielding portion, whereby the insulating joint formed by said strip remains unaltered during the expansions and contractions of said yielding portion.

2. A tubular electric resistance comprising a band of electrically conducting material provided between its edges with a longitrdinal central corrugation adapted to ex- Egnd and to contract transversely, said band ing formed into an helix with the edges overlapping on either side of said corrugation so as to constitute a tubular element having a lengthwise elasticity, and a strip of electrically insulating material inserted between the adjacent edges of said band and independent of said corrugation, whereby the insulating joint formed by said strip remains unaltered during the expansions and contractions of said corrugation. i

In testimony Where I have signed my name to this specification.

JEAN GUSTAVE BASSIERE. 

